Naturespeak A naturalist's view of the world

October 20, 2008

Butter Please, Not Margarine

Filed under: Uncategorized — wykes @ 7:22 pm

  The Yellow-rumped Warbler may be the most common warbler species in North America, but the chance to view one up close and personal should not be slighted.  My chance was afforded by a confrontation between a window and a warbler in which the glass proved to be the victor. Fortunately, the bird’s glass encounter was a glancing blow and therefore not fatal. The affair left her in a temporarily loopy state. I scooped it up (see above) just as the cobwebs were clearing.

  Yellow-rumps are one of the dozens of warbler species that pass through the region in the fall migration. Fall warblers are notorious for their non-descript non-breeding coloration (thus the section in the Peterson Guide labeled “confusing fall warblers”).  Even in her dull autumn wrappings, however, this bird is easy to identify because of the brilliant yellow rump (see here) and the splash of yellow on the sides of the breast. There are three other yellow-bottomed fall warblers but they are mere margarine when compared to this one. Many folks simply refer to the Yellow-rumps as “butterbutts” to save effort and time.

  Unlike their fellow warblers who pass through quickly, the butter birds tend to linger later into the season. Some even elect to over winter here.   They can do such a thing because they are “diet switchers.” This doesn’t mean chosing lowfat over chocolate, but instead means switching from an insect diet to vegetarian fare. That’s not an easy thing to do.  They can exploit a variety of plant resources and stomach hard to digest foods such as waxy fruit and poison ivy berries.

  It might seem odd to us humans, but the white, wrinkled fruit of the Poison Ivy vine is actually one of the preferred winter foods of this bird. A good crop of these berries often determines how long wintering yellow-rumps will stick around. Should the winter food crop fail, these birds have the where-with-all to move further south. This trait is not common among most migrant birds who are usually bound by instinct to live (or die) with their chosen winter location. Butterbutts can, and will, move along.

  The woods and thickets are now brimming with these little dynamos. Most are still feeding on insects (this one was picking spiders under the eaves). They flit about in small flocks while constantly talking to each other. Listen here to the constant chatter of a group of butterbottoms (Yellow-rump Chatter)– you’ll note the constant “t-check, t-check” call.

  After a few minutes, the bird in my hand was not uttering gentle “t-checks.” It had recovered to the point where her calls had morphed into some angry avian profanity. I opened my hand to release her and she remained in place long enough for me to take one last portrait (see here). She finally launched back into the bush to join her fellow birds-a wiser bird with a headache and a long cold season ahead.

1 Comment »

  1. I can’t add your rss feed to my reader, what could be the problem?

    Comment by Ellie — March 4, 2009 @ 6:32 pm

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